researches of E. Wasmann (1901). Here the individual is hermaphrodite--a
most exceptional condition among insects--and lays a large egg, whence
is usually hatched a fully-developed adult! Here then we find that all
the early stages, usual in the higher insects, are omitted from the
life-story.

Interesting comparison may be made between the total duration of various
insect life-stories. To some extent at least, the length of an insect's
life is correlated with its size, its food, the season of the year when
it breeds. Small insects have, as a rule, shorter lives than large ones;
those whose larvae devour highly nutritive food generally develop more
quickly than those which have to live on dry, poor, substances;
life-cycles follow one another most rapidly in summer weather when
temperature is high and food plentiful.

In early chapters we have already noticed the long aquatic life of the
larva and nymph of a dragon-fly, relatively a large insect, and the
rapid multiplication of the repeated summer broods of virgin aphids (p.
18). Within the one order of the Coleoptera it is instructive to compare
the small jumping leaf-beetles, the 'turnip-flies' of the farmer, whose
larvae mine in the green tissues, and complete their transformations so
rapidly that several successive broods appear in the spring and early
summer, with the larger click-beetles whose larvae, the equally
notorious 'wireworms,' feed on roots for three or four years before they
become fully grown. Among the Diptera, the 'leather-jacket' grub of the
crane-fly, feeding like the wireworm on roots, has a larval life
extending through the greater part of a year, while the maggot of the
bluebottle, feeding on a rich meat diet, becomes mature in a few days.
As examples of excessively long life-cycles the 'thirteen-year' and
'seventeen-year' cicads of North America, described by C.L. Marlatt